This command is useful when your download is interrupted. You can resume it by using the -c (or --continue) option.

This time you can try to download Debian 11 ISO file, and then press Ctrl + C to cancel the download before the command finishes.

wget https://gemmei.ftp.acc.umu.se/debian-cd/current/amd64/iso-cd/debian-11.4.0-amd64-netinst.iso

To resume the download, add the -c option. Note that this will only work if you run this command in the same directory as the incomplete file.

wget -c https://gemmei.ftp.acc.umu.se/debian-cd/current/amd64/iso-cd/debian-11.4.0-amd64-netinst.iso

It is worth mentioning that not all links support resuming downloads.